SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a870d3e92377ccee8bc14e48cb48dc4112dd51f4ab9026921fe80e4380e67afb' 
  AND token = 'lPj+JAfqtZU4Ksk1Df9Nix+R7ggw5TrTRu9VH2gzGCQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}